(08/23/22) CHASE, La. — Rain is a welcome sight in northeast Louisiana these days, so when storm clouds gathered the morning of Aug. 18, sweet potato farmers who have been contending with dry conditions all summer breathed a sigh of relief.
Their fields were getting some much-needed rainfall, and as an added bonus, they got a break from the August heat that usually accompanies the annual field day at the LSU AgCenter Sweet Potato Research Station.
The event typically features field tours where attendees can get an up-close look at research trials. While this year’s program had to be shifted beneath the cover of a shed and tents, it was still packed with about 100 attendees and more than a dozen speakers who delivered the latest information on their projects and issues the industry is facing.
One of the highlights was AgCenter sweet potato breeder Don La Bonte’s presentation on new varieties being developed to meet evolving industry demands. It’s not an easy task, as sweet potato varieties need to provide high yields, look nice, taste good and offer some degree of resistance to pests.
“There’s a lot of work that goes into coming up with those very few lines that make it to the industry,” La Bonte said, showing attendees several crates filled with some of his most promising varieties.
It has been tough to improve on the Beauregard and Orleans varieties — high-performing industry standbys that, even after being on the market for years, still account for much of Louisiana’s sweet potato acreage. Data for 2022 isn’t available yet, but the state typically grows 7,000 to 8,000 acres of sweet potatoes across about seven parishes.
La Bonte has been focusing recently on finding varieties that stand up to nematodes — microscopic roundworms that can wreak havoc on sweet potato yields and quality. Some of the nematodes of concern are the Southern root-knot, guava root-knot and reniform species.
He has found a couple of promising possibilities, including LA 18-100, which is resistant to the Southern root-knot nematode and produces earlier potatoes and higher yields than many other varieties. La Bonte said he has a “keen interest” in this variety as a potential release because it is flavorful and bears many similarities to the popular Beauregard, including skin tone, quality and No. 1 count. No. 1 potatoes are those favored by fresh market consumers.
Other varieties La Bonte is examining include LA 19-42, which has good skinning resistance and could be an ideal potato for the processing sector, and a few purple-fleshed varieties.
Nematode-resistant varieties are an exciting development, said AgCenter nematologist Tristan Watson.
“We don’t have a lot of management tactics,” he said.
Watson is part of a national group working on a project seeking to identify resistant varieties — particularly those resistant to the devastating guava root-knot nematode — as well as study the genetic mechanisms that determine resistance and new nematode detection methods such as sensors. He also is studying several control methods, including nematicides and planting winter cover crops to prevent growth of weeds that serve as hosts for nematodes.
The initiative is funded by a $5 million grant from the U.S. Department of Agriculture National Institute of Food and Agriculture. More information is online at www.sweetarmor.org.
Weed control is another challenge in sweet potato farming. As a specialty crop, there are relatively few herbicides labeled for it. Because of changing federal rules for registering products, the number of herbicide options available for all crops could soon dwindle, said AgCenter weed scientist Donnie Miller.
“That’s something we need to keep our eye on going forward,” Miller said.
There is some good news for sweet potato farmers, however. A new product expected to hit the market next year could offer a way to control weeds between 21 and 35 days after planting. “We have a hole in sweet potato weed management” during that time period currently, Miller said.
He also advised growers to be aware of the problems caused by herbicide drift. Sweet potatoes do not tolerate some products used on other crops. Even small amounts of those herbicides that drift onto a sweet potato field can reduce yields, Miller said.
The AgCenter Sweet Potato Research Station is the only facility in the United States dedicated solely to sweet potato research. One of the biggest ways it has impacted the industry is through its Foundation Seed Program, which was established in the 1940s and provides high-quality planting material to growers.
In 1999, this program was upgraded to incorporate virus testing, ensuring that growers receive “clean” seed that are free of viruses. The program became part of the National Clean Plant Network in 2015.
AgCenter plant pathologist Chris Clark has been a key part of these efforts. He said a study has been underway for the past year looking at the economic advantages of planting clean seed, which tend to result in better yields.
He encouraged growers to use seed from the program.
“I think not only do we underestimate the benefits of clean seed,” he said. “We also overestimate the cost.”
Clark officially retired a few days before the field day after a long career with the AgCenter. He arrived on the LSU campus as an assistant professor in 1977. Among other accomplishments, he was involved in the breeding process for many varieties, including the popular Beauregard, which was a breakthrough at the time of its release in the late 1980s.
“Dr. Clark has selflessly dedicated his career to sweet potato on the state, national and international levels,” said Tara Smith, resident coordinator of the Sweet Potato Research Station. “He has left an indelible mark.”
She presented Clark a plaque recognizing his 45 years of service to the AgCenter and Louisiana agriculture.
Mike Erwin, a farm specialist who has worked at the research station for nearly 40 years, also received a plaque. He has announced plans to retire in January.
“He’s always here. He gives 110%,” Smith said, recalling that Erwin was one of the first people she met at the research station when she was named sweet potato specialist in 2006.
Matt Lee, interim LSU vice president for agriculture, praised AgCenter scientists’ work to not only conduct research but extend the findings to the industry.
Agriculture is a top priority in LSU President William F. Tate IV’s Scholarship First Agenda, which also includes national defense as a focus area. The Sweet Potato Research Station and all of the AgCenter play an important role in both of these areas, Lee said.
“Food security is national security,” he said.
Mike Strain, commissioner of the Louisiana Department of Agriculture and Forestry, echoed Lee’s comments. The global need for safe, affordable and nutritious food is growing.
“The world is getting to be a mighty hungry place,” Strain said, adding that more people are coming to appreciate sweet potatoes as a valuable food item.
That makes research on the crop increasingly critical, he said.
The Louisiana Sweet Potato Commission, which falls under Strain’s purview, has given $890,000 to the AgCenter for research since 2008, said commission director René Simon.
Others on the field day program included:
— AgCenter agronomist Arthur Villordon, who is studying sweet potatoes’ response to phosphorous and potassium. It appears that different varieties require different amounts of these nutrients, he said. Villordon also is studying the benefits of irrigation, which he said can make a big difference in yields during dry years like this one.
— AgCenter extension associate Myrl Sistrunk, who said the dry summer and high input costs have made for a challenging growing season. He said about 45% of Louisiana sweet potatoes are sold on the fresh market while 55% are sent to processing facilities, mostly ones that make frozen products.
— AgCenter entomologist Jeff Davis, who discussed his collaboration with North Carolina biotechnology company AgBiome to identify biological control options for the sweet potato weevil.
— AgCenter Northeast Region director Melissa Cater, who noted that this year’s field day was the first held at the station since 2018. The 2019 field day took place at Black Gold Farms, and the 2020 and 2021 iterations were held virtually due to the coronavirus pandemic.
— Kay Rentzel, executive director of the National Sweet Potato Council, who reported on her organization’s efforts to advocate for farmers on the national level.
LSU AgCenter sweet potato breeder Don La Bonte holds LA 18-100 and Beauregard sweet potatoes side by side to show their similarities during a field day Aug. 18. Photo by Olivia McClure/LSU AgCenter
LA 18-100 sweet potatoes are seen at a field day Aug. 18. This line, which has several desirable traits, is being evaluated by the LSU AgCenter. Photo by Olivia McClure/LSU AgCenter
Attendees of an Aug. 18 field day pass around a jar containing a sample of a sweet potato with nematode damage. Photo by Olivia McClure/LSU AgCenter
Matt Lee, interim LSU vice president for agriculture, speaks at a field day Aug. 18 at the LSU AgCenter Sweet Potato Research Station. Photo by Olivia McClure/LSU AgCenter
LSU AgCenter agronomist Arthur Villordon stands on a trailer filled with crates of sweet potatoes as he discusses his research during a field day Aug. 18. Photo by Olivia McClure/LSU AgCenter